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Dairy Crest relies on vision solution for perfect bottling

Dairy Crest is the UK's leading chilled dairy foods company and manufactures a range of everyday dairy brands including the award-winning Cathedral City cheddar, Clover spread, Country Life butter and FRijj. In addition, they also supply milk to retailers throughout the country, from major supermarkets to village stores, while their milkmen deliver to thousands of homes throughout England and Wales every day.

Benefitting from a £15 million investment in 2001, the capacity of the site at Chadwell, Essex doubled to create a state-of-the-art facility that was capable of processing 400 million litres of milk a year. To cope with the huge volume of milk bottled at the factory and to ensure all products were distributed to customers in perfect condition required a robust and reliable vision solution. However, saddled with the original vision system that was proving complicated and unreliable, Dairy Crest came to PCS Industries in search of a solution.

The Solution

After careful consultation, PCS designed and built a modular system to perform a number of inspection tasks on standard plastic milk bottles ranging from 2 to 6 pints and a 2 litre version. The system consisted of a DVT 545 colour camera, Mitsubishi PLC, Touch-panel PC and a high speed reject unit. A custom graphical user interface (GUI) runs on the touch-panel PC and handles the communication between the various modules and this ensures that Dairy Crest operatives never have to work with either the vision or PLC software as all relevant settings and parameters are accessed through the GUI. The system also offers further capabilities as it has inputs for additional sensors for label detection, cap foil presence and faults from the filler.

The modular system is installed on three separate yet identical production lines and checks the presence, colour, height and angle of each bottle cap, running at a speed of 220 bottles per minute 24/7. The first line runs 4 pint, 6 pint and 2 litre bottles. Line 2 concentrates on the 2 pint bottles and the third line is dedicated to 4 pint bottles.

After filling, the bottles are automatically channelled along a conveyor and taken to the inspection area. The DVT cameras are housed in wash-down enclosures and fixed to the side of each line where they capture the required images as each bottle passes along the line. The advanced vision capabilities of the DVT camera ensures all required inspection checks are performed from just one image. At the same time, the system also tracks filler faults (e.g. under fill), missing labels and missing foil. All 'passes' continue to an automated packing area where they are loaded onto trolleys for distribution to the customer.

Those bottles which do not conform are removed from the conveyor by an advanced high speed reject system which directs the bottles onto a separate reject conveyor. The reject element was tasked with removing filled bottles from the line running at 220 bottles per minute without causing the loss of any liquid or a decrease in line speed. The PCS solution accomplishes this even when the bottles are close together. The reject unit is synchronised to the speed of the conveyor via an encoder so will alter its speed with that of the production line.

Statistics are kept which show counts for all the different reject reasons and this data is automatically uploaded from the PLC to the plant's data capture system. This allows easy access to important information to ensure productivity is maintained at maximum output levels.

The end result

Steve Cottam, Packaging Area Engineering Manager at Dairy Crest commented, "The system has proven to be robust and reliable and is incredibly easy to use. We have seen a significant decrease in customer complaints from leaking bottles and the systems have required little or no adjustment or maintenance. PCS listened to our objectives and have fulfilled and exceeded all expectations by delivering a cost-effective solution which has improved our productivity. Due to the success of this vision solution, we are due to install two additional systems and intend to roll this out across all lines within Chadwell with a recommendation to use the PCS units country wide."

See it in action